Carbon capture: Transport and storage

Transporting and then storing carbon dioxide below ground are the final stages of carbon capture and storage (CCS). The safe and secure burial of CO2 is the most difficult part of the process – and prompts the greatest public concern.

Yet scientists and engineers are confident that safe transport and storage is possible. Natural CO2 has been securely trapped underground for many tens of millions of years, for example, under large swathes of Italy, central France, south-east Germany and the south-western US. And the expertise and technology required for transporting, injecting and monitoring the gas can be directly derived from the oil and gas industries.

Challenges of storage

After capture, CO2 is stored kilometres beneath Earth’s surface. Microscopic pores in reservoir rock, such as sandstone, can be filled with dissolved or liquid CO2. Above this reservoir, layers of impermeable rock, such as shale and clays, prevent the CO2 migrating to the surface. As a guide, a storage site is expected to operate with less than 1 per cent CO2 loss to the surface over the next 10,000 years.

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Most countries have potential storage capacity for many decades-worth of CO2. Europe has vast storage potential offshore beneath the North and Baltic seas. The rocks beneath the UK seabed account for 35 per cent of all European Union storage capacity.

Though capacity is not a problem, finding storage sites is not easy, due to the general public’s concern about …